SEMI DETAILED LESSON PLAN IN TLE 9 - TECHNICAL DRAFTING
Lesson Topic: Alphabet of Lines
Grade Level: 9
Time Allotment: 1 hour
Learning Area: Technology and Livelihood Education (TLE) - Technical Drafting
I. OBJECTIVES
At the end of the lesson, students should be able to:
1. Identify and describe the different types of lines used in technical drawing.
2. Appreciate the importance of using the correct Alphabet of Lines in creating clear
and precise technical drawings.
3. Accurately draw the Alphabet of Lines using proper measurements and drafting
tools.
II. SUBJECT MATTER
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Topic: Alphabet of Lines
Materials: Visual aids, projector, drafting tools (T-square, triangles, pencils),
worksheets
Reference: MELC Guide for TLE 9
III. PROCEDURE
A. Preliminary Activities
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Prayer: The teacher will play a short prayer video while students observe silence
and reflect.
Classroom Management: The teacher reminds students of classroom rules and
proper behavior during discussions and activities.
Checking of Attendance: The teacher asks, “Who is absent today?” and records
attendance.
B. Review (10 minutes) – 4 Pics 1 Word
Strategy: Gamification and active recall
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The teacher displays 4 pictures related to drafting instruments. Students will guess
the correct word.
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Final challenge: The last round shows four pictures related to the new lesson.
Students guess the lesson title based on the images.
C. Motivation (5 minutes) – Connecting to Language
Strategy: Contextualization and student inquiry
1. What comes to mind when you hear the word alphabet?
2. Why do we need an alphabet? (To form words and communicate clearly)
3. Engineers, architects, and designers have their own alphabet—instead of letters,
they use lines.
4. Can you interpret the drawing?
5. Introduce the Alphabet of Lines as the language of drafting.
D. Presentation of the New Lesson (10 minutes)
Strategy: Visual presentation and direct instruction
1. Display a chart of the Alphabet of Lines and introduce each type.
2. Explain the function of each line with examples:
o Visible Line – Shows the actual shape of an object.
o Hidden Line – Represents parts that cannot be seen.
o Center Line – Used for symmetry and circular objects.
o Dimension Line – Indicates measurements.
o Extension Line – Extends a dimension line.
o Leader Line – Points to specific features.
o Cutting Plane Line – Shows where an object is sectioned.
o Phantom Line – Represents movement or alternate positions.
o Break Line – Shortens large objects.
o Section Line – Shows areas of material cut in section views.
3. Demonstrate how each line is drawn using proper techniques.
4. Where do we see these lines in real life? (Blueprints, house plans, maps, etc.)
E. Application Activity 1: Identifying Alphabet of Lines in a Picture (15 minutes)
Strategy: Visual analysis and guided questioning
1. Show a detailed technical drawing.
2. Group activity: Students analyze the drawing and identify different lines.
3. Discussion questions:
o Which types of lines can you identify?
o What is the purpose of these lines in the drawing?
o How do these lines help in understanding the structure or object?
o Why is it important to use the correct line types in technical drawings?
o How do these relate to real-world applications?
4. Class presentation: Each group presents their findings.
Rubric for Evaluation (12 points)
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Identification of Lines (4 pts) – Identifies most lines correctly.
Explanation of Purpose (4 pts) – Explains function and significance of lines.
Presentation (4 pts) – Clear and organized presentation.
Activity 2: Hands-on Drawing of the Alphabet of Lines (15 minutes)
(Experiential learning & Guided Practice)
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Instructions:
1. Use a ruler and pencil for straight lines.
2. Follow the correct thickness for each line type.
3. Label each line properly.
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Line Type
Line Appearance
Measurement Guide
Visible Line
Thick Continuous Line
0.66mm thickness
Hidden Line
Dashed Line
(Short dashes)
Long-short-long
Pattern
3mm dash
1mm space
5mm long
1mm space
2mm short
0.3 mm thickness
3mm arrow size
2mm past dimension line
45-degree angle
2mm part
5mm dashes
2mm space,
Center Line
Dimension and
extension line
Section line
Cutting plane line
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Thin line with arrowhead
Thin continuous line extending
pass object
Thin diagonal lines for cross
sections
Thick dashed line
Rubric:
o 5 points – All lines drawn accurately with proper thickness.
o 3 points – Some mistakes in measurement or thickness.
o 1 point – Lines are incorrect or missing.
G. Generalization (5 minutes) Reflective Discussion
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What did we learn today?
Summary: Just as letters form words, lines form technical drawings. The Alphabet of
Lines helps engineers, architects, and designers communicate accurately.
How will this knowledge help in real-life situations?
IV. EVALUATION: (Summative assessment – 10 minutes)
Written quiz (10 points) – Multiple choice and matching)
Multiple-Choice Questions
1. Which type of line is used to represent the visible edges of an object?
a) Hidden Line
b) Center Line
c) Object Line
d) Phantom Line
(Answer: c) Object Line
2. What is the purpose of a hidden line in a technical drawing?
a) To show the symmetry of an object
b) To indicate invisible edges or details
c) To highlight the center of a circle
d) To represent a cutting plane
(Answer: b) To indicate invisible edges or details
3. Which line is used to indicate the axis of symmetrical objects like cylinders or holes?
a) Dimension Line
b) Center Line
c) Section Line
d) Cutting Plane Line
(Answer: b) Center Line
4. A long dash followed by two short dashes is a characteristic of which type of line?
a) Center Line
b) Phantom Line
c) Section Line
d) Dimension Line
(Answer: b) Phantom Line
5. Which of the following lines is used to show where an object is cut to reveal internal
details?
a) Section Line
b) Cutting Plane Line
c) Break Line
d) Extension Line
(Answer: b) Cutting Plane Line
Matching Type Questions
Instructions: Match the type of line in Column A with its correct description in Column B.
Column A (Type of Line)
1. Object Line
2. Dimension Line
3. Hidden Line
4. Center Line
5. Section Line
Column B (Description)
a. Represents hidden edges of an object
b. Indicates the center of circles and arcs
c. Shows the physical shape of an object
d. Used to measure the size of an object
e. Used to represent a cut surface in a drawing
V.ASSIGNMENT (Enrichment Activity) (Independent learning)
Research and bring an example of a real-life technical drawing
Write a short reflection: "How did the Alphabet of Lines help make the drawing clearer
Prepared by: Mary Ann Lenie O. Solis